Study Guide Chapters 12 – 14 Key

1. Define: electronegativity, dipole, dipole moment, Van der Waals Forces. electronegativity: The tendency of a bonded atom to attract electrons towards itself. (example: when F bonds to O the F pulls the electrons closer to it because it’s electronegativity is higher.) Dipole: a polar molecule Dipole moment: measurement of the amount of polarity. (example: a molecule that is more polar would have a greater dipole moment). Van der Waals Forces: Attractive forces between adjacent molecules. (example: the bigger a molecule is and the more polar it is the better it is able to attract adjacent molecules).

2. State the differences and similarities between ionic, covalent, and metallic bonds (see the “Four Types of Bonding” table in your notebook).

3. Contrast the number of shared pairs, the number of electrons, the strength, and the length within single, double, and triple bonds. Single bonds have one shared pair of electrons (two shared electrons). They are the weakest and longest of the covalent bonds. Triple bonds have three shared pairs of electrons (6 shared electrons). They are the strongest and shortest of the covalent bonds. Double bonds have two shared pairs of electrons (four shared electrons). They have a strength and length between that of single and triple bonds.

4. What are the differences between shared pairs and unshared pairs? Shared pairs of electrons are represented in Lewis structures by –’s. They represent bonds and belong to both atoms which they connect. Unshared pairs (lone pairs) also called lone pairs are represented in Lewis structures by a pair of x ’s,  ’s or o ’s. They belong only to the atom which they are placed on.

4. What are the differences between shared pairs and unshared pairs?

5. How does electronegativity vary within the groups and periods of the periodic table? The closer an atom is to “F” in the periodic table the higher the electronegativity. (Remember that the noble gases have no electronegativities).

6. How can we predict the type of bond formed between atoms by using (a) a periodic table and (b) a table of electronegativities. A bond between a metal and a nonmetal is ionic. A bond between metals is metallic. A bond between different nonmetal atoms is polar covalent. A bond between the same nonmetal atoms is nonpolar covalent. The electronegativity difference can be used to determine bond type as well. –If the electronegativity difference is greater than 1.67 between two atoms the bond between them is ionic. –If the electronegativity difference is less than 1.67 the bond is covalent.

7. How do differences in electronegativities influence bond strength. The greater the electronegativity difference between two atoms the stronger the bond is between them.

8. Complete the table:

9. Contrast the attractive forces within solids, liquids, and gases at room temperature. At any given temperature a solid has the greatest attractive forces and a gas has the least. The attractive forces in a liquid are somewhere in between.

10. How do the size and polarity of molecules affect their Van der Waals forces. The larger and more polar a molecule is the greater its Van der Waals forces.

11. PBr 3

11. NO 2 -

11. ClF 2 +

11. FNO 2

11. N 3 -

11. CF 4